/*
 * rev-parse.c
 *
 * Copyright (C) Linus Torvalds, 2005
 */
#include "cache.h"
#include "commit.h"
#include "refs.h"
#include "quote.h"
#include "builtin.h"

#define DO_REVS		1
#define DO_NOREV	2
#define DO_FLAGS	4
#define DO_NONFLAGS	8
static int filter = ~0;

static const char *def;

#define NORMAL 0
#define REVERSED 1
static int show_type = NORMAL;
static int symbolic;
static int abbrev;
static int output_sq;

static int revs_count;

/*
 * Some arguments are relevant "revision" arguments,
 * others are about output format or other details.
 * This sorts it all out.
 */
static int is_rev_argument(const char *arg)
{
	static const char *rev_args[] = {
		"--all",
		"--bisect",
		"--dense",
		"--branches",
		"--header",
		"--max-age=",
		"--max-count=",
		"--min-age=",
		"--no-merges",
		"--objects",
		"--objects-edge",
		"--parents",
		"--pretty",
		"--remotes",
		"--sparse",
		"--tags",
		"--topo-order",
		"--date-order",
		"--unpacked",
		NULL
	};
	const char **p = rev_args;

	/* accept -<digit>, like traditional "head" */
	if ((*arg == '-') && isdigit(arg[1]))
		return 1;

	for (;;) {
		const char *str = *p++;
		int len;
		if (!str)
			return 0;
		len = strlen(str);
		if (!strcmp(arg, str) ||
		    (str[len-1] == '=' && !strncmp(arg, str, len)))
			return 1;
	}
}

/* Output argument as a string, either SQ or normal */
static void show(const char *arg)
{
	if (output_sq) {
		int sq = '\'', ch;

		putchar(sq);
		while ((ch = *arg++)) {
			if (ch == sq)
				fputs("'\\'", stdout);
			putchar(ch);
		}
		putchar(sq);
		putchar(' ');
	}
	else
		puts(arg);
}

/* Output a revision, only if filter allows it */
static void show_rev(int type, const unsigned char *sha1, const char *name)
{
	if (!(filter & DO_REVS))
		return;
	def = NULL;
	revs_count++;

	if (type != show_type)
		putchar('^');
	if (symbolic && name)
		show(name);
	else if (abbrev)
		show(find_unique_abbrev(sha1, abbrev));
	else
		show(sha1_to_hex(sha1));
}

/* Output a flag, only if filter allows it. */
static int show_flag(const char *arg)
{
	if (!(filter & DO_FLAGS))
		return 0;
	if (filter & (is_rev_argument(arg) ? DO_REVS : DO_NOREV)) {
		show(arg);
		return 1;
	}
	return 0;
}

static void show_default(void)
{
	const char *s = def;

	if (s) {
		unsigned char sha1[20];

		def = NULL;
		if (!get_sha1(s, sha1)) {
			show_rev(NORMAL, sha1, s);
			return;
		}
	}
}

static int show_reference(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
{
	show_rev(NORMAL, sha1, refname);
	return 0;
}

static void show_datestring(const char *flag, const char *datestr)
{
	static char buffer[100];

	/* date handling requires both flags and revs */
	if ((filter & (DO_FLAGS | DO_REVS)) != (DO_FLAGS | DO_REVS))
		return;
	snprintf(buffer, sizeof(buffer), "%s%lu", flag, approxidate(datestr));
	show(buffer);
}

static int show_file(const char *arg)
{
	show_default();
	if ((filter & (DO_NONFLAGS|DO_NOREV)) == (DO_NONFLAGS|DO_NOREV)) {
		show(arg);
		return 1;
	}
	return 0;
}

static int try_difference(const char *arg)
{
	char *dotdot;
	unsigned char sha1[20];
	unsigned char end[20];
	const char *next;
	const char *this;
	int symmetric;

	if (!(dotdot = strstr(arg, "..")))
		return 0;
	next = dotdot + 2;
	this = arg;
	symmetric = (*next == '.');

	*dotdot = 0;
	next += symmetric;

	if (!*next)
		next = "HEAD";
	if (dotdot == arg)
		this = "HEAD";
	if (!get_sha1(this, sha1) && !get_sha1(next, end)) {
		show_rev(NORMAL, end, next);
		show_rev(symmetric ? NORMAL : REVERSED, sha1, this);
		if (symmetric) {
			struct commit_list *exclude;
			struct commit *a, *b;
			a = lookup_commit_reference(sha1);
			b = lookup_commit_reference(end);
			exclude = get_merge_bases(a, b, 1);
			while (exclude) {
				struct commit_list *n = exclude->next;
				show_rev(REVERSED,
					 exclude->item->object.sha1,NULL);
				free(exclude);
				exclude = n;
			}
		}
		return 1;
	}
	*dotdot = '.';
	return 0;
}

int cmd_rev_parse(int argc, const char **argv, const char *prefix)
{
	int i, as_is = 0, verify = 0;
	unsigned char sha1[20];

	git_config(git_default_config);

	for (i = 1; i < argc; i++) {
		const char *arg = argv[i];

		if (as_is) {
			if (show_file(arg) && as_is < 2)
				verify_filename(prefix, arg);
			continue;
		}
		if (!strcmp(arg,"-n")) {
			if (++i >= argc)
				die("-n requires an argument");
			if ((filter & DO_FLAGS) && (filter & DO_REVS)) {
				show(arg);
				show(argv[i]);
			}
			continue;
		}
		if (!strncmp(arg,"-n",2)) {
			if ((filter & DO_FLAGS) && (filter & DO_REVS))
				show(arg);
			continue;
		}

		if (*arg == '-') {
			if (!strcmp(arg, "--")) {
				as_is = 2;
				/* Pass on the "--" if we show anything but files.. */
				if (filter & (DO_FLAGS | DO_REVS))
					show_file(arg);
				continue;
			}
			if (!strcmp(arg, "--default")) {
				def = argv[i+1];
				i++;
				continue;
			}
			if (!strcmp(arg, "--revs-only")) {
				filter &= ~DO_NOREV;
				continue;
			}
			if (!strcmp(arg, "--no-revs")) {
				filter &= ~DO_REVS;
				continue;
			}
			if (!strcmp(arg, "--flags")) {
				filter &= ~DO_NONFLAGS;
				continue;
			}
			if (!strcmp(arg, "--no-flags")) {
				filter &= ~DO_FLAGS;
				continue;
			}
			if (!strcmp(arg, "--verify")) {
				filter &= ~(DO_FLAGS|DO_NOREV);
				verify = 1;
				continue;
			}
			if (!strcmp(arg, "--short") ||
			    !strncmp(arg, "--short=", 8)) {
				filter &= ~(DO_FLAGS|DO_NOREV);
				verify = 1;
				abbrev = DEFAULT_ABBREV;
				if (arg[7] == '=')
					abbrev = strtoul(arg + 8, NULL, 10);
				if (abbrev < MINIMUM_ABBREV)
					abbrev = MINIMUM_ABBREV;
				else if (40 <= abbrev)
					abbrev = 40;
				continue;
			}
			if (!strcmp(arg, "--sq")) {
				output_sq = 1;
				continue;
			}
			if (!strcmp(arg, "--not")) {
				show_type ^= REVERSED;
				continue;
			}
			if (!strcmp(arg, "--symbolic")) {
				symbolic = 1;
				continue;
			}
			if (!strcmp(arg, "--all")) {
				for_each_ref(show_reference, NULL);
				continue;
			}
			if (!strcmp(arg, "--branches")) {
				for_each_branch_ref(show_reference, NULL);
				continue;
			}
			if (!strcmp(arg, "--tags")) {
				for_each_tag_ref(show_reference, NULL);
				continue;
			}
			if (!strcmp(arg, "--remotes")) {
				for_each_remote_ref(show_reference, NULL);
				continue;
			}
			if (!strcmp(arg, "--show-prefix")) {
				if (prefix)
					puts(prefix);
				continue;
			}
			if (!strcmp(arg, "--show-cdup")) {
				const char *pfx = prefix;
				while (pfx) {
					pfx = strchr(pfx, '/');
					if (pfx) {
						pfx++;
						printf("../");
					}
				}
				putchar('\n');
				continue;
			}
			if (!strcmp(arg, "--git-dir")) {
				const char *gitdir = getenv(GIT_DIR_ENVIRONMENT);
				static char cwd[PATH_MAX];
				if (gitdir) {
					puts(gitdir);
					continue;
				}
				if (!prefix) {
					puts(".git");
					continue;
				}
				if (!getcwd(cwd, PATH_MAX))
					die("unable to get current working directory");
				printf("%s/.git\n", cwd);
				continue;
			}
			if (!strncmp(arg, "--since=", 8)) {
				show_datestring("--max-age=", arg+8);
				continue;
			}
			if (!strncmp(arg, "--after=", 8)) {
				show_datestring("--max-age=", arg+8);
				continue;
			}
			if (!strncmp(arg, "--before=", 9)) {
				show_datestring("--min-age=", arg+9);
				continue;
			}
			if (!strncmp(arg, "--until=", 8)) {
				show_datestring("--min-age=", arg+8);
				continue;
			}
			if (show_flag(arg) && verify)
				die("Needed a single revision");
			continue;
		}

		/* Not a flag argument */
		if (try_difference(arg))
			continue;
		if (!get_sha1(arg, sha1)) {
			show_rev(NORMAL, sha1, arg);
			continue;
		}
		if (*arg == '^' && !get_sha1(arg+1, sha1)) {
			show_rev(REVERSED, sha1, arg+1);
			continue;
		}
		as_is = 1;
		if (!show_file(arg))
			continue;
		if (verify)
			die("Needed a single revision");
		verify_filename(prefix, arg);
	}
	show_default();
	if (verify && revs_count != 1)
		die("Needed a single revision");
	return 0;
}